Structure and Function of Coordination Sites in Metal Trafficking ProteinsPublic Deposited
Many metal ions are of critical importance in many cellular functions. The very properties of these metal ions that make them useful also make them toxic to the cell. In the course of evolution, many metal ion homeostasis systems have developed to provide balance between the necessity and toxicity of these nutrients. All of the metal trafficking proteins that have been structurally characterized to date form a unique subset of the known metalloproteins, and have coordination chemistry tailored by nature to their specific role. Here we present insights into the coordination chemistry of Atx1, a yeast copper chaperone protein, PcoC, a bacterial copper detoxification protein, and ZntA, a bacterial zinc export pump. Despite the fact that these proteins bind different metal ions, and are found in different organisms, they share common characteristics that set them apart from other metalloproteins. They bind their metal ions with coordination chemistry unlike that for other known proteins that bind the same metal. Additionally, they tend to exhibit metal-ion-dependent interactions. As bioinorganic chemists uncover more of these trafficking and transport pathways, other interesting biological coordination environments will likely be revealed.